Abstract
Ionic liquids (ILs) have been widely investigated for the pretreatment and deconstruction of lignocellulosic feedstocks. However, the modes of interaction between IL-anions and cations, and plant cell wall polymers, namely, cellulose, hemicellulose, and lignin, as well as the resulting ultrastructural changes are still unclear. In this study, we investigated the atomic level and suprastructural interactions of microcrystalline cellulose, birchwood xylan, and organosolv lignin with 1,3-dialkylimidazolium ILs having varying sizes of carboxylate anions. Analysis by 13C NMR spectroscopy indicated that cellulose and lignin exhibited stronger hydrogen bonding with acetate ions than with formate ions, as evidenced by greater chemical shift changes. Small-angle X-ray scattering analysis showed that while both cellulose and xylan adopted a single-stranded conformation in acetate-ILs, twice as many acetate ions were bound to one anhydroglucose unit than to an anhydroxylose unit. We also determined that a minimum of seven representative carbohydrate units must interact with an anion for that IL to effectively dissolve cellulose or xylan. Lignin is associated as groups of four polymer molecules in formate-ILs and dispersed as single molecules in acetate-ILs, which indicates that it is highly soluble in the latter. In summary, our study demonstrated that 1,3-dialkylimidazolium acetates displayed stronger binding interactions with cellulose and lignin, as compared to formates, and thus have superior potential to fractionate these polymers from lignocellulosic feedstocks.
| Original language | English |
|---|---|
| Pages (from-to) | 2164-2172 |
| Number of pages | 9 |
| Journal | Biomacromolecules |
| Volume | 24 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 8 2023 |
Funding
This work was supported by the Research Council of Norway (BioMim project) and the U.S. Forest Service, Southern Research Station (Award #19-JV-594 1130131-026). Partial funding was also obtained from the U.S. DOE Office of Science, under the Biological and Environmental Research Program (FWP ERKP752–Genomic Science Program, and FWP ERKP291–The Center for Structural Molecular Biology). This research used resources of the Advanced Photon Source; a U.S. Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract DE-AC05-00OR22725. This manuscript has been coauthored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This work was supported by the Research Council of Norway (BioMim project) and the U.S. Forest Service, Southern Research Station (Award #19-JV-594 1130131-026). Partial funding was also obtained from the U.S. DOE Office of Science, under the Biological and Environmental Research Program (FWP ERKP752-Genomic Science Program, and FWP ERKP291-The Center for Structural Molecular Biology). This research used resources of the Advanced Photon Source; a U.S. Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract DE-AC05-00OR22725. This manuscript has been coauthored by UT-Battelle, LLC, under Contract No. DEAC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). The authors thank Dr. Carlos A. Steren from the Department of Chemistry, the University of Tennessee Knoxville, for assisting with the NMR experiments. The authors also thank Dr. Byeongdu Lee at Advanced Photo Source, Argonne National Laboratory, for useful discussions on SAXS data analysis. Finally, the authors would like to thank Dr. Yachin Cohen from the Department of Chemical Engineering, Technion Israel Institute of Technology, Haifa, for email correspondence on biopolymer ion binding calculations.
| Funders | Funder number |
|---|---|
| DOE Public Access Plan | |
| United States Government | |
| U.S. Department of Energy | |
| Office of Science | |
| Biological and Environmental Research | FWP ERKP291, FWP ERKP752 |
| Argonne National Laboratory | DE-AC02-06CH11357 |
| Oak Ridge National Laboratory | DE-AC05-00OR22725 |
| U.S. Forest Service | 19-JV-594 1130131-026 |
| University of Tennessee, Knoxville | |
| UT-Battelle | |
| Norges Forskningsråd | |
| Technion-Israel Institute of Technology | |
| Department of Chemical Engineering, Universiti Teknologi Petronas |